Seattle's worst traffic congestion "hotspot" is Interstate 5 southbound from 128th Street Southwest in Everett to Pike Street in Seattle -- about a 20-mile stretch of the freeway.

That's according to Kirkland-based traffic data company INRIX, which just released its traffic hotspot report this week, ranking 25 U.S. cities based on their congestion hotspots and expected costs of that congestion over the next decade.

What you probably didn't know was that Seattle has 2,675 such hotspots.

That number, calculated through INRIX's "impact factor," is projected to cost drivers $15 billion by 2026, according to the report.